1. Field of the Invention
The present invention relates generally to winding filaments, and, more particularly, to a winding of high packing density and a method of making.
2. Description of Related Art
This invention is related to my pending application Deep Nested Filament Winding, Ser. No. 07/270,885, filed Nov. 14, 1988, now U.S. Pat. No. 4,925,125, which is a division of Ser. No. 07/069,353, filed Jul. 2, 1987, now abandoned.
There are situations in which it is desirable to be able to pay out a metal wire or optical fiber of considerable length for use as a data link. For example, many present day weapon systems include a launched missile with a wire or fiber optic data link wound on a bobbin or spool which pays out at a very high rate of speed during use.
Several criteria must be met in order to provide a satisfactory winding which can act as a missile data link. First of all, payout must be accomplished with a minimum of tension on the filament to prevent breakage, or in the case of an optical fiber even to prevent micro-bending which reduces signal transmission. Secondly, the winding should be stable so as to permit storage without collapsing from its wound configuration. Lastly, the winding should be dense and compact so as to take as little space as necessary.
Certain present day high speed filament dispensers have the filament in one layer nest between turns of adjacent layers. To maintain this condition, in certain known dispensers each layer is stepped back several turns from the underlying layer This results in tapered ends for the winding which reduces volumetric efficiency.
A disadvantage especially found in cylindrical layered windings is the frictional drag on payout resulting from an outer layer being removed from an underlying layer. One way of reducing this problem is to provide a winding having an inside-out payout which not only provides exceptional volumetric efficiency but allows the winding to be stored without being subjected to undesirably high levels of tensile stress. This latter point is important especially for optical fiber cables which are subject to static fatigue and optical signal attenuation due to loads imposed by winding.
Known inside payout dispensers employ a "basket weave" winding technique which results in a substantial amount of empty space reducing volumetric efficiency. Moreover, the relatively large effective pitch of such a winding causes a correspondingly large modulation in instantaneous payout velocity reducing achievable vehicle speed for a given filament strength.
It is also desirable for windings, especially inside payout windings, to have squared ends. However, closely packed windings with squared ends are not easily wound, and in the past were not obtainable by high speed, automatic techniques.
The foregoing problems have been exacerbated by the problem of crossovers. Crossovers heretofore have generally advanced a full pitch at each crossover region of a winding turn and/or have resulted in windings with irregular (i.e., non-squared) ends. See in this connection, Winding Long Slender Coils By The Orthocyclic Method by Halder W. C. Aamot, Special Report 128, U.S. Army Material Command, Feb. 1969. Such uncontrolled crossovers have required frequent manual "massage" to minimize winding disturbances, bulges, and other irregularities which may prevent successful winding and payout, and reduce volumetric efficiency.